Telephone switchboard switching system



Dec. 13, 1938. A. R. BONORDEN 2,139,800 .TELEPHONE SWITCHBOARD SWITCHINGSYSTEM Filed Aug. 26, 1936 v 8 Sheets-Sheet 1' n F/GJ 1 -5/[2 MPG/MALFIG. /8

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INVENTOR FIG, F/QZ FIG"? BVARBO/YORDEM M ATTORNEY Dec. 13, 1938. A.RIBONORDE N 2,139,800

.TELEPHONE SWITCHBOARD SWITCHING SYSTEM Filed Aug. 26, 1956 8SheetsSheet 2 /b0 335 F/G.2

llllllllllll l nun-yum 208 207 (325 mfi b: 2// J 209 I 6% INVENTOR & ByARBONORDEN A TTOR/LIEK Dec. 13, 1938. R BONORDEN 2,139,800

TELEPHONE SWITCHBOARD SWITCHING SYSTEM Filed Aug. 26, 1936 8Sheets-Sheet 3 com com CORD CIRCUIT 309 CIRCUIT CIRCUIT A TTORNEV I Dec.13, '1938. A. R. BONORDEN TELEPHONE SWITCHBOARD SWITCHING SYSTEM 7 FiledAugQ'26, 1 936 1 8 sheets-sheet 4 400 F/G.4

ATTORNEY %c. H, 3938. A. R. BONORDEN 2,139,8fifi TELEPHONE SWITCHBOARDSWITCHING SYSTEM Filed Aug. 26, l956 8 Sheets-Shet 5 F/G5 5/0 CIRCUITc090 com 500 CIRCUIT CIRCUIT INVENTOR ARBOA/ORDEN rraeusr Dec. 13, W38.A. R. BONORDEN 2,139,860

TELEPHONE SWITCHBOARD SWITCHING SYSTEM Filed Aug. 26, 1936 8Sheets-Sheet 6 F7616 F/a'aA lNl ENT 0R 4. R. BQ/VORDE A TT'ORNEV %c. 13,1938. A. R. BONORDEN 2,139,800

TELEPHONE SWITCHBOARD SWI TCHING SYSTEM Filed Aug. 26, 1936 8Sheets-Sheet 7 FIG. 7

CORD C 0R0 C 0R0 CIRCUIT I C/RCU/ 7' CIRCUIT MAINS/MAL W 14 T TOPNEVDec. 13, 193%. A. R. QBONORDEN 2,139,80G

. TELEPHONE SWITCHBOARD SWITCHING SYSTEM Filed Aug. 26, 1936 8Sheet-Shet 8 FIG. 8 600 CORD CORD CORD Q/RCU/T CIRCUIT CIRCUIT llll IllIIHHI HIIHIIi ||||H ullllulllllll I A A A em" OFFICE UNITED STATES PATELEPHONE SWITCHBOARD SWITCHING SYSTEM Allen Rudolf Bonorden, Fanwood,N. 3., assignor to American Telephone and Telegraph Company, acorporation of New York Application August 26, 1936, Serial No. 98,056 9Claims. (01. 17948) This invention relates to communication sysondaryanswering appearance at any position of tems and more particularly tosupervising and the multiple type of telephone switchboard.

maintaining private, or order, wire service over Another feature is theprovision of having a intercity communication trunk circuits betweensequence circuit associated with the trunk cirtelephone test boardattendants located in differcuits or the positional keysets. 5 entcities. Another feature is the provision of recalling the An object ofthe invention is to permit an atattendant at a primary position afterthe signal tendant at a telephone switchboard or test board has beentransferred to another position and the in one locality to be connected.with any one of a attendant at the latter position has failed to wplurality of attendants at a telephone switchanswer. 10 board or testboard in a different locality. Another feature is the provision of atransfer It is essential in telephone test board operation key so thatfor night operation all signals of dif in telephone systems forattendants at different ferent trunk circuits normally appearing indiflocalities having charge of a particular service at ferent primarypositions may be caused to appear 3 5 their respective test boards toobtain direct comat some one position used as a night or light loadmunication with each other and consequently it position. is desirable tohave an arrangement which will A more complete understanding of theinvenfacilitate certain direct communication or pertion may be obtainedfrom the accompanying mit of an incoming call being rapidly transferreddrawings in which to an attendant responsible for a particular serv-Figures 1, 2 and 3 represent an arrangement of 20 In both 13011 andtelephone Practice e the invention when interconnected in accordancefore known the transfer of calls, received over with the block diagramFig. 1-A, wherein Fig. l certain trunks or line circuits, is possible toa shows two-way communication lines and associvery limited extent, thatis, the facilities at presated line equipment, Fig. 2 a control circuitfor ent permit the transfer to one or at the most transferring calls,and Fig. 3 answering jacks two points in the ofiice. and lamps,associated busy lamps, position trans- According to the presentinvention the facilifer keys, position sequence circuit relays and. tiesprovide for each position or section in a line cord circuits. The cordcircuits are shown in deof telephone test boards to become a potentialtail by Fig. 1-B. transfer point and in the larger of said oiiices Figs.4 and 5 represent another arrangement 30 these facilities extend toarrangements for transof the invention, when interconnected inaccordferring a call to any one of a plurality of poslance with theblock diagram l-A, wherein Fig. i tions or sections. In other words anattendant at shows two-way communication lines and assoc-1 a multipletype of telephone switchboard may ated line equipment including acrossbar switch upon receiving an incoming call over an intercity andFig. 5 shows answering jacks and lamps, communication trunk circuit,transfer the inbusy lamps, position transfer keys, cord circuits comingcall signal to any particular one of a pluof the type shown by Fig. 1-Band a relay type rality of trunk lamps, each of which is located atcontrol circuit. a different position or section. in the switchboard.Figs. 6, '7 and 8 represent still another arrange- The multiple type ofswitchboard may comprise ment of the invention when interconnected 1n 40two or more sections, each section having one or accordance with theblock diagram 6-A, wherein more operators or attendants positions. Fig.6 shows two-way communication lines and A feature of the presentinvention is that it associated line equipment including a crossbarprovides a more flexible arrangement than hereswitch and Fig. 7 showsanswering jacks and tofore known in that an incoming call signal lamps,busy lamps, position transfer keys, cord may be transferred to a signallamp at any one circuits of the type shown by Fig. 1-13 and a of evenmore than twenty positions. different relay type control circuit thanthat Another feature is that an incoming call signal shown in Fig. 5.may b transferred a p at any one of a Fig. 8 is an alternativearrangement of Fig. '7

plurality of telephone switchboard positions and which uses a controlCircuit Consisting f a 50 then again transferred to another lamp at oneof tary type Stepping switch the other positions.

Still another feature is that the arrangement may provide by propercross-connections for any Referring to Figs. 1, 2 and 3, I00 is aninter- 56 trunk circuit to have either a primary or a secoffice line,which terminates in jacks 3G0, 3M and Figures 1, 2 and 3 302 ofpositions 1, 2, and 3, respectively. Associated with these jacks areanswering lamps 303, 304 and 305 and busy lamps 306, 301 and 308,respectively. The attendant at each position is provided with a cordcircuit, conventionally represented by the boxes 309, 3! 0 and 3| I andshown in detail by Fig. 1- B. Calls may be answered with plug I03 byplugging into the jack associated with the lighted answering lamp, ororiginated with plug I04 by plugging into the jack of the line selectedfor an outgoing call and ringing with key I05. Additional jacks,answering and busy lamps may be provided at additional positions, notshown. As shown in the drawings, position 3 is cross-connected by theconductor 200, so that the associated answering lamp 305 is lighted onan incoming call, that is, position 3 is a primary answering position.Position 2 is not thus cross-connected, its lamp 304 is lighted only ona transferred'call, and is accordingly a' secondary answering position.Position 1 is cross-connected by the conductor 20I so that when nightkey 3I2 is operated, it is then a socalled night position at which allcalls incoming over line I00 and over all other lines with night keyssimilarly operated, are answered. Under this Condition it is a primaryposition; when the night keys are not operated it is a secondaryposition. The night key 362 may be multipled with a number of lines in apredetermined group so that all these grouped lines may be answered atposition 1 when said key is operated. It is to be understood that anyposition in the switchboard line up may be arranged as either a primaryor secondary answering position by suitable cross-connection. Anyposition may also be a night position.

In order to transfer incoming calls from one position to another, lineI00 is provided with a rotary type stepping switch, for which 202 is thestepping magnet. This magnet causes the brush arms 203 and 204 to movearound the contact banks 205 and 206, respectively.

Each terminal of bank 205 is connected to a conductor leading to ananswering lamp at the respective positions whereby each lamp may beselectively lighted as required. Each contact of bank 206 is connectedto a conductor to which ground is selectively connected by one of thepositional transfer keys as 3I3, 3M, 3I5, which in effecting a transferidentifies the position to which the call is to be transferred. The linebeing transferred is identified by the insertion of the plug I03 of cordcircuit C in the associated line jack and by then operating listeningkey I06. In order to use a transfer circuit arrangement common to allpositions, a so-called sequence circuit is used. This consists of relaysSIS, 3I'I, 3I8 and 3I9, 320 and 32I, which are arranged in a mannersimilar tothe relays of an automatic listening, straightforward trunkingsystem, which is well known in the telephone art. Thus arrangement makesthe common transfer equipment available to only one position at a timeand thereby avoids the possibility of interference if two'attendantsshould attempt to transfer calls simultaneously. Another feature of thesequence circuit is the arrangement whereby calls awaiting transfer arehandled progressively through the sequence, but not necessarily in theorder in which transfers are attempted.

In the description before given, particular reI- erence was made to theline I 00 and its associated apparatus. A similar description alsoapplies to the other lines IN and I02. A more complete understanding ofthe operation of the arrangement of Figs. 1, 2 and 3 may be obtainedfrom the following detailed description.

Let it be assumed that an attendant at a distant telephone test boarddesires to communicate with the attendant located at position 2 andselecting the line Q00, applies ringing current thereto. Ringing relayI01 then operates through condenser I08 and the left outer breakcontacts of cut-01f relay II 0 and closes an obvious circuit through thewinding of relay I09, which operates and looks through its inner rightcontacts to ground on the left inner contacts of relay IIO.

Relay I09, in operating connects battery with its left outer frontcontacts to conductor I I I, thence through cross-connection 200 andover conductor 343 to ground through lamp 305. The usual audible alarmand auxiliary position pilot lamp may be operated by inserting a lowresistive relay between all lamps in a position and this ground. Also,relay I09 connects battery with its right outer front contacts toconductor 322, lighting busy lamps 306, 307 and 308, and busy lamps atother positions not shown. The attendant at position 3 now responds byinserting the answering plug of a cord circuit which is conventionallyrepresented by a box 3| I, intojack 302. This cord circuit, as beforestated, is represented in detail by Fig. 1-B, to which the descriptionnow refers. A circuit is closed from battery through the winding ofsleeve relay 524 over sleeve conductor of plug I03 and jack 302, overconductor 323, through winding of relay H0 and right winding of marginalrelay II2 to ground. arranged for supervision, supervisory relay H3operates, thereby connecting resistance I I4 in shunt with supervisorylamp H5 which remains dark. If line I 00' is not arranged forsupervision, relay II3 does not operate and lamp I I5 is lighted in acircuit from battery through resistance IIB to ground on the contacts ofsleeve relay I25, which, operated, when plug I03 was inserted into jack302. Relay I 50 operates but relay II 2 does not operate at this time.In operating, relay H0 disconnects the circuit of relay I01 from theconductor of line I 00, opens the locking circuit of relay I09 whichreleases, connects battery with its right inner contacts to conductor322 thereby maintaining the lighting of the busy lamps. after therelease of relay I09, and with its right outer front contacts connectsground to the left inner front contacts of relay H2 so that relay I I2may lock when it subsequently operates. The release of relay I09disconnects battery from conductor III, thereby extinguishing lamp 305.The attendant at position 3 now operates listening key I06, therebyestablishing communication over line I00 with the attendant at thedistant office. Having been informed that communication. with theattendant at position 2 is desired, the attendant at position 3 nowtransfers the call by operating the position transfer key 3%, which isthe key at position 3 assigned to the transfer of calls to position 2. Acircuit is now closed from battery.324, through the winding of relay320, and right operated contacts of key 3M to ground. Sequence circuitrelay 320 operates and a circuit is closed from battery through thewinding of relay 32!, lower operated front contacts of relay 320 toconductor 325. If neither relay 3I8 or 356 of positions 1 and 2 isoperated, due to the previous engagement of the sequence circuit bythese positions, the circuit before traced is extended over conductor325, through lower back contacts of relay 3I8, over conductor 321,through lower If the line is back contacts of relay 3I6, over conductor326, 75

through winding of relay 2111 to ground 211 on the break contacts ofrelay 208. Relays 201 and 321 operate in this circuit. Relay 2111 closesa circuit from battery through the winding of slow releasing relay 208and contacts 239 and 211) to ground. Relay 2118 in operating disconnectsground 211, and the circuit is maintained through contacts 211 of relay2191 which is locked operated. If either relay 313 or 318 werepreviously operated, then the circuit through the winding of relay 321is open at the back contacts of either relay or 318. If relay 316 isoperated its winding is connected to battery 324 through the upper innerbreak contacts of relays 319 and 321; if relay 318 is operated, battery324 is connected through the upper inner break contacts of relay 321.

A general description of the operation of the sequence circuit, which asbefore stated is used in the telephone art for straightforward trunkingwill now be given. Relay 316 may be said to be in the first, relay 318in an intermediate and relay 321) in the last position. If relays 318and 313 are operated, and lines are awaiting service in the,last andfirst positions, relay 3211 is opererated but relay 316 is not operated,since its operating path is disconnected by the lower break contacts ofrelay 318. When relay 318 releases, conductor 321 is transferred fromthe winding of relay 319 to conductor 325 by the continuity contacts ofrelay 318, thereby holding relay 231 operated through the lower operatedcontacts of relay 3211 and the winding of relay 321, which operates.Relay 316 does not operate since its circuit, previously opened at relay319 is also opened by the upper inner break contacts of relay 321 beforerelay 319 releases to close its portion of said path. Relays 311, 319and 321 are slightly slow to release to assure this feature. When relay3211 releases, releasing relay 321, the circuit through relay 2111 isopened and this relay releases, releasing in turn slow releasing relay2118, which after an interval reconnects ground 211. During this openinterval, relay 316, and also relay 318, if this relay is again awaitingoperation, now operate. Relay 316, however, disconnects conductor 321,so that now relay 311, and not relay 313 or 321, operates. Thus, linesawaiting connection are served by the sequence circuit sequentially inaccordance with their numbered position in the sequence, and not inaccordance with the order of their call for service. In Fig. 3 onlythree pairs of sequencerelays are shown corresponding to positions 1, 2and 3 respectively. For additional positions, sequence relays may beadded establishing the same interconnections between positions as areshown,

battery 324 being connected to the relays of the last position as it isshown connected to relays 323 and 321.

Relay 321 operating in response to the operation of key 314 and relay3211 as before described connects ground through its upper outercontacts to conductor 328, thence through the left con tacts of key 314to conductor 329 and the secend terminal of hunting switch bank 206.This is for the purpose of marking the stopping point for brush arm 234and associated arm 2113, as will hereinafter be described. Relay 321 inoperating also disconnects conductor 344, with its upper inner contacts,from battery 324, thereby preventing the operation of relays 318 and316, if a transfer key at positions 1 or 2 should now be operated, andalso with its lower inner contacts closes a circuit which is traced frombattery through the right and left series connected windings .of relay212, over conductor 330, through lower inner contacts of relay 321,upper contacts of relay 3211 to ground through the positional releaselamp 331. Relay 212 operates in this circuit but lamp 331 does not lightbecause of the high resistance of the right winding of relay 212. Relay212 in operating closes a circuit from ground through its contacts, leftinner back contacts of relay 213, and Winding of slow releasing relay214 to battery, Relay 214 operates and closes a circuit from battery 215through resistance 216, left contacts of relay 214, over conductor 332,through lower outer operated contacts of relay 321, to conductor 333,which is also indicated on Fig. 1-B to which reference should now bemade. From conductor 333 the circuit continues through the lower outeroperated contacts of listening-key 106, over conductor 111, throughsleeve conductors of plug 103 and jack 332 and thence over the sleevecircuit before traced. Since battery 215 is of higher voltage than theregular sleeve circuit battery 118 marginal relay 112 now operatesthrough its right winding and looks through its left winding and leftinner contacts to ground on the right outer front contacts of sleeverelay 111). Relay 112 in operating closes a circuit from battery throughthe left outer back contacts of relay 1113, through right front contactsof relay 112, over conductor 211, through winding of relay 218, overconductor 219 to ground on the right outer contacts of relay 1 19. Relay218 operates and closes a circuit from battery through the winding andbreak contacts of stepping magnet 2112, right outer contacts of relay218, over conductor 2211, through right inner contacts of relay 213,back contacts of relay 221 to ground through operated contacts 222 and223 of relay 214. Magnet 202 by means of its self-interrupting contactsrotates brush arms 233 and 2134 around their respective contact banks inthe direction indicated by the arrows. The brush arms 2113 and 2114 areshown resting normally on bank contacts No. 1; it should be understood,however, that these brush arms may rest normally on any one of thecontacts, the position depending on the particular set of contactsrequired by the last selection. Relay 218 also closes a circuit frombattery through the winding of relay 221, over conductor 221, throughleft contacts of relay 218, over conductor 223 to brush arm 2114. Whenbrush arm 2114 reaches contact 2 of bank 2133 the circuit is continuedover the path previously traced to ground on the upper outer operatedcontact of relay 321. Relay 221 operates opening the operating path ofmagnet 282 thus causing the selector brush arms 2133 and 206 to remainon contact 2 of their respective banks. Relay 221 operated also, closinga circuit traceable from ground on the operated contacts 223 and 222 ofrelay 214, front contacts of relay 221, to battery through the windingof relay 213, which operates and locks through its left inner frontcontacts to ground on the contacts of relay 212. Relay 213 also opensthe circuit of relay 214 which releases after an interval, but beforereleasing a circuit is closed from ground through contacts 223, rightouter contacts of relay 213, over conductor 224, right inner contacts ofrelay 218, over conductor 225, and through right winding of relay 119 tobattery. Relay 113 operates and looks through its left winding and innercontacts to ground on the left outer operated contacts of relay 112. Thecircuit of relay 2H8 is opened and this relay releases, releasing relay2.2.1. When relay 213 operated and relay 2I4 released as beforedescribed a short-circuit was closed around the right winding of relay2I2, which is traced from the common terminal of the two windings ofrelay 2I2, through left outer contacts of relay 2| 3 to battery on theright normally closed contacts of relay 2M. Relay 2I2 now holds on itsleft winding,

and the resistance of its circuit being reduced lamp 33I is now lighted,which is an indication to the attendant at position 3 that thetransferring apparatus has functioned. Key 3M is accordingly released,effecting the release of relays 2I2, 2I3, 329 and 32I, and plug IE3 iswithdrawn from jack 3B2. Sleeve relay IIE! now releases also releasingrelay II 2. Relay H9, however, remains operated through the right outerback contacts of relay I I5, and with its right inner contacts maintainsbattery on conductor 322, the busy lamps at all positions remaininglighted. The release ofirelay I I 2 closes a circuit from battery on theleft outer contacts of relay I 09, right back contacts of relay II2,leftouter front contacts of relay II9, over conductor 225, over brush arm253, contact 2 of bank 255, over conductor 334 and to ground throughanswering lamp 336 at position 2.

The attendant at position 2 now responds by inserting into jack 31H theplug of cord circuit 3), thereby operating over the sleeve circuitsleeve relay Ht, but not the marginal relay II 2. The

circuit through the left winding of relay II 9 is opened, and this relayreleases opening the circuit, before traced, for lamp 354, which isextinguished. The busy lamps, however, remain lighted, due to batterybeing reconnected to conductor 322 by the right inner contacts of relayH5. When the listening key of cord circuit SIB is operated, theattendant at position 2 is then in communication with the distant ofiiceover the line I59. The flexibility of the transferring fea ture of myinvention is such, that now, should the attendant at position 2 desireto transfer the call, this may be done in the same manner as theoriginal call was transferred from position 3 to 2. If, for instance atransfer to position 1 is required, the attendant at position 2 operateskey 35!, thereby causing sequence relays M5 and 3I9 to function inconnection with the common relays 258, 251, 2I2, 22I, 2M and 2I3 in thesame manner as did relays 320 and 32L In this case ground is connectedover conductor 342 to terminal No. l of bank 256 and stepping magnetZIlZrotates brush arm 2% until this grounded terminal is found. Lamp 353 islighted over conductor 345, terminal No. 1 of bank 255, brush arm 2133,over conductor 226 and the circuit previously traced for lamp 394.

Position 1, (or any position) as before stated may be arranged to beused as a night position. Night key Hi2 is shown associated with lineI551, over conductor 335. Other lines may be grouped with line I55 fornight answering by connecting conductor 335 to the correspondingconductors of these lines.

In a similar manner night keys 336 and 331 are associated with lines IGIand I02, over conductors 338 and 339. When key 312 is operated andrelays I01 and I59 operate, as before described, in response to incomingringing current, a circuit is traced from battery through the contactsof key 3E2, over conductor 335, through left inner operated contacts ofrelay I09, over conductor 52$ cross-connecter conductor 340 and toground through lamp 303, which lights. The lamps at the primarypositions also light, but

are not answered, since these positions are unattended at this time.

The operation of the arrangement of Figs. 1, 2 and 3 have been describedfor an incoming call. This arrangement may also be used for outgoingcalls. The attendant at position 3, for instance, may originate a callby plugging into jack 302, with calling plug I94 of cord circuit C.Cut-off relay H is operated and the busy lamps at all positions arelighted as before described. The attendant now operates ringing key I05,connecting thereby, ringing current source I2I to the tip conductor andground I22 to the ring conductor. When the distant attendant answers,communication is established by operating listening key I55, connectingthereby the telephone circuit I23.

Figures 4 and 5 Referring to another arrangement of the inventiondisclosed by Figs. 4 and 5, in Fig. 4 are shown three intercommunicationlines 400, 4M and 462, which are arranged to cooperate with a crossbarswitch CB which is of the same general construction as that described inPatent No. 2,021,329, issued November 19, 1935 to J. N. Reynolds, fromwhich patent a complete description may be obtained. The function ofswitch GB is to cooperate over tional transfer keys, as 536, 531, 538 or539 of Fig. 5 in order to transfer calls to various posi-- tions in atelephone switchboard line-up. The switch CE is shown with lines G00, 4!and 492 connected to cooperate with verticals 1, 2 and 10, respectively.Intervening verticals, 3, 4, 5, 6, 7

and 8 are omitted as being unnecessary for the purpose of thisdescription, and are symbolized by vertical 9, which is shownunconnected. Only four horizontals are shown, each of which representspositions respectively 1, 2 and 3 of Fig. 5, and position 4, not shown.Horizontals 5, 6, 7, 8, 9 and 10 are not shown since these are notnecessary in describing the invention. By means of the switch CB tenlines, as 400, 4!, 402, etc., may be served, and transferred to any oneof ten positions. By using two switches any one of twenty lines-ortrunks may be transferred to any one of ten positions, or alternatively,any one of ten lines may be transferred to any one of twenty positions.

When a call is initiated over one of the lines, say line 355, relays 353and 554 operate so as to light answering lamp 553 at position 3 overconductor 555, and the busy lamps at all positions are lighted overconductor 556. Assuming that the night key 552 is operated, answeringlamp 556 at the position will also be lighted. This isin accordance withcross-connections 4 55 and 556. The answering lamps for line 5553 atposition 1, when key 555 is not operated and at position 2 are lightedonly on transferred calls. Any position may be cross-connected so as tofunction as either a primary or secondary position. In response to alighted answering lamp, the attendants plug into the answering jacks557, 508 or 555 with a cord circuit 518, 5 or 5I2, conventionallyrepresented by a box but shown in detail by Fig. 1B, therebyextinguishing the lighted answering lamps. In order'to transfer a callfrom one position to another, a position transfer key, as 536, 537, 538or 539, corresponding to the position to which the transfer is to bemade is operated. This causes the sequence circuit shown at the bottomof Fig. 5 to function, provided it is not already in use at some otherposition. In operattransfer trunk 500 with posi ing, the sequencecircuit causes a horizontal or selecting magnet 401, 408, 409 or M0,corresponding to the position to which the transfer is to be made, to beenergized and then also a vertical or holding magnet 4, M2 or M3,corresponding to the line 400, 40l or 402, which is to be transferred.The contacts of switch CB, corresponding to the intersection of theoperated vertical and horizontal, are now closed. When the transferapparatus has completed its operation a signal is given to the attendantby the lighting of the positional release lamp 5l3, M or 515. Theoperated position key is then released, and when the plug of the cordcircuit, which was used to answer the call, is withdrawn from theanswering jack, the lamp at the position to which the transfer is to bemade is lighted. In the description hereinbefore given, particularreference was made to the line 400 and its associated apparatus. Asimilar description also applies to the other lines MN and 002. A morecomplete understanding of the operation of the invention may be obtainedby tracing the progress of a call as hereinafter described.

Let it be assumed that an attendant at a distant switchboard desires toinitiate a call over the line 000 for the attendant located at position2, which is accessible to line 400 only as a secondary answeringposition. Relay 403 operates on incoming ringing current throughcondenser MA and operates relay 404 through an obvious circuit. Relay404 locks through its right inner contacts to ground on the leftcontacts of cut-off, or sleeve, relay M0, and connects battery with itsright outer contacts to conductor 500, thereby lighting busy lamps H,M8, 5!!) and lamps at other positions not shown. With its left outerfront contacts relay 004 connects battery to conductor M0, thence overcross-connecter 405 and conductor 505 to ground through answering lamp503, which lights at position 3. The attendant thereat answers byinserting the plug of cord circuit 5l2, that is, plug I03 or the cordcircuit shown by Fig. 1-B, into jack 500, thereby closing a circuit overthe sleeve conductors of plug I03, jack 509 and conductor 520 throughthe winding of cut-off relay M5 and the right winding of marginal relay5H. Relay M5 operates but not relay 5. Relay M5 opens the lockingcircuit of relay 000, which releases, and connects battery with itsright inner contacts to conductor 500 maintaining the lighting of thebusy lamps. The release of relay 404 removes battery from conductor M6,extinguishing lamp 503. The attendant at position 3 is now incommunication with the distant attendant over line 000, when listeningkey 100 is operated. On being informed that a transfer to position 2 isdesired, position transfer key 538 is accordingly operated, closingthereby a circuit from battery 52! through thewinding of sequence relay522 to ground on the right operated contacts of key 538. Relay 522operates, and assuming that neither relay 523 nor 524 is operated acircuit is closed from ground 050 through normally closed contacts ofslow releasing relay M9, through winding of relay 020, over conductor525, through normally closed lower contacts of relays 524 and 523, loweroperated front contacts of relay- 522 and winding of relay 526 tobattery. Relays 420 and 525 operate. Relay 420 in operating closes anobvious circuit through the winding of relay M9 and locks to ground onits own contacts. Relay 0 I 9 operates and disconnects ground M 8. Relay526 disconnects with its upper inner contacts battery 52! from conductor52?, thereby preventing the operation of relays 523 or 524, if anattendant at position 1 or 2 should now attempt to transfer a call;connects ground on its upper outer contacts to conductor 528, whence itis extended through the left operated contacts of key 538, overconductor 529 to battery through the winding of horizontal selectingmagnet 008, which is energized. Another circuit is closed from groundthrough lamp 565, over conductor 530, through upper contacts of relay022, lower inner contacts of relay 520, over conductor 53!, and throughthe series connected windings of relay 42! to battery. Relay 02!operates but due to the high resistance of its right winding lamp 5l5 isnot lighted. Relay lZl closes a circuit from ground through left innerback contacts of relay 422 to battery through the winding of slowrelease relay 423, which operates and connects with its left contactsbattery 024 in series with resistance 425 to conductor 532, thencethrough lower outer contacts of relay 520 to conductor 333. Referringnow to cord circuit C of Fig. 1-13 the circuit continues through lowerouter contacts of operated listening key I00 to sleeve conductor H1,thence over the sleeve conductors of plug I03 and jack 500 through thewindings of relays M5 and M1 as herein before traced. Due to the highervoltage of battery 020, marginal relay M! now operates and looks frombattery through its left winding and inner contacts to ground on theright outer front contacts of relay H5 and connects ground on its rightcontacts to conductor 420, thence through winding of vertical holdingmagnet 4l3 over conductor 42'! to battery on theleft outer back contactsof relay 000. Magnet M3 operates and connects ground with its leftcontacts to conductor 328, whence the circuit continues through leftinner back contacts of relay 429 over conductor'030 and through theright winding of relay 022 to battery. Relay 022 operates and locksthrough its left winding and inner contacts to ground on the operatedcontacts of relay 42! and releases relay 023. Relay 423 in releasingconnects ground through its right inner contacts and right contacts ofrelay 022 to conductor 43!, thence through left outer break contacts andright winding of relay 029 to battery on the left outer operated frontcontacts of relay M1. Relay 029 operates and looks through its leftwinding and inner front contacts to ground on conductor 020. The leftouter contacts and left inner front contacts of relay 029 are arrangedso that the latter close before the former break, thereby assuring thelocking up of relay 429 before its operating circuit is broken.

When relay 423 released as herein before described it closed a circuitfrom battery through its right outer break contacts, left outer operatedcontacts of relay 022 to the junction point between the left and rightwindings of relay 42L This is equivalent to short-circuiting the rightwinding of relay 02! and lamp 5E5 now lights, relay 02! holding on itsleft winding. The attendant now knows that the selection has beencompleted and releases key 530, which releases relays 522, 520, 020, M9,02!, 022 and magnet 408. The plug N is now withdrawn from jack 509 whichreleases relays M5 and M1. Because of the right outer continuitycontacts of relay M5 ground is connected to conductor 432, before groundis removed from the left locking winding of relay All. Consequently,relay M1 does not release removing ground from conductor 420 until thelocking circuit through the right contacts of magnet M3 is established.

With magnets 408 and M3 operated consecutively as herein beforedescribed, contacts 433 of the crossbar switch CB are closed and whenrelay 4H released a circuit was closed from battery on its left outercontacts over conductor 43G, through contacts 433, over conductor 435 toground through lamp 502, which lights. Battery is connected to conductor505 by the right contacts of relay 429, thereby maintaining the lightingof the busy lamps. The attendant at position 2 now responds with theanswering plug of cord circuit 5, thereby again operating relay 4! 5,but not marginal relay MI. The operation of relay M5 releases magnet M3,opening the switch contacts 433 and extinguishing lamp 582. As in thecase of the'arrangement of Figs. 1, 2 and 3 the attendant at position 2may now, if such is required re-transfer the call to any other position.

Position 1, (or any other position) as before stated, is arranged to beused as a night position. When key 5534 is operated, battery on thecontacts of this key is extended over conductor 533 to the left innercontacts of relay 464 so that when this relay operates on an incomingcall over line 4430, battery is connected to lamp 59! over conductor436, cross-connection 426 and conductor 534. Other lines, not shown. inthe same group as line 40!! may be multipled with line 468 overconductor 43'! so that their respective lamps are also lighted onincoming calls. when key 594 is operated. In like manner another nightkey 535 may be arranged to connect for night answering, another group oflines, of which group, lines 4i and 402 are shown. I

The operation of the arrangement of Figs. 4 and 5 has been described foran incoming call. It may also be used for outgoing calls in the samemanner as was described for the arrangement of Figs. 1, 2 and 3. 7

Figures 6, 7 and 8 Referring now to another arrangement of the inventionas disclosed by Figs. 6, 7 and .8, the comb nation of Figs. 6 and 7 willnow be discussed. In Fig. 6 are shown three intercommunication lines60!], 6M and 602 which are arranged to cooperate with a cross-bar switchCB similar to that of Fig. 4. The function of switch CE isto cooperateover transfer trunk 7 with positional transfer keys. as for instance,I35, 731, 738 or 139, of Fig. '7, to transfer calls to various positionsin the switch board line up. The switch CB is shown with lines 600. 6!!!and 682 connected to function with verticals 1, 2 and 10. respectively.Intervening verticals 3, 4, 5, 6, 7 and 8 are omitted as beingunnecessary for the purpose of thisdescription, and are symbolized by avertical 9. which is shown unconnected. .Only four horizontals areshown. each of which represents positions, respectively, tion 4 notshown. Horizontals 5, 6, '7, 8, 9 and 10 are not shown since these arenot necessary in describing the invention By means of the switch CB tenlines as 5M, SM, 682, etc., may be served and transferred to any one often positions.

By using two switches any one of twenty lines may be transferred to anyone of ten positions or alternatively, any one of ten lines'may betransferred to any one of twenty positions. Furthermore, by using an Nnumber of cross-bar switches connected together horizontally there isprovided space for ten times N number of trunk.

l, 2 and 3 of Fig. 7. and posi-V circuits to ten positions ofswitchboard; by using M number of cross-bar switches connected togethervertically there is provided space for ten trunk circuits to ten times Mpositions; and by using N number of cross-bar switches connectedtogether horizontally and M number of cross-bar switches connectedtogether vertically there is provided by the joint arrangement ten timesN' The answering lamps for line 68!] at positon 1,

when key 704 is not operated and at position 2 are lighted only ontransferred calls. Any position may be cross-connected so as to functionas either a primary or secondary position. In response to a lightedanswering lamp, the attendants plug into the answering jacks I91. 768 or799, with a cord circuit Hi3, H! or H2, conventionally represented by abox but shown in detail by Fig. l-B, thereby extinguishing the lightedanswering lamps. In order to transfer a call from one position toanother, a position transfer key such as 136, 13?, 138 or 139,corresponding to the position to which the transfer is to be made, isoperated. This causes the relay control circuit, consisting ofpositional relays l'ls, H4 and H5 H7 and M3 to function, provided it isnot already in use. In operating, the control circuit causes a selectingmagnet 681, 663, 589 or 6H], corresponding to the position to which thetransfer is to be made to be energized and then also a holding magnet6H, M2 or M3 to the line 6M, 60! or 602 which is to be transferred. Thecontacts of switch CB corresponding to the intersection of the operatedvertical and horizontal are now closed. When the transfer apparatus hascompleted its operation, a signal is given to the attendant by thelighting of the positional release lamp H5, 729 or 12!, The operatedposition key is then released, and when the plug of the cord circuit,which was used to answer the call is withdrawn from the answering jack,the lamp at the position to which the transfer is to be made is lighted.A more tacts of cut-off or sleeve relay 6M, connects bat tery with itsright outer contacts to conductor m6, thereby lighting busy lamps I22,123, and 725 and lamps at other positions not shown. With its left outerfront contacts relay 6504 connects battery to conductor i323, thenceover crossconnection 665 and conductor 185 to ground through answeringlamp 103, which lights at position 3. The attendant thereat answersbyand common relaysv 1 I 6,'

corresponding plug I03 of the cord circuit shown in Fig. 1-43 into jackH39, thereby closing a circuit to ground over the sleeve conductors ofplug H33, jack HR and conductor through the winding of cutoff relay 6Mand the right winding of marginal relay 6l5. Relay 6M, but not relayEH5, operates. Relay GIG opens the locking circuit of relay 6%, whichreleases, and connects battery with its right inner contacts toconductor Hi6, maintaining the lighting of the busy lamps. The releaseof relay 5% removes battery from conductors 623 and N35 connected inseries, thereby extinguishing lamp 183. The attendant at position 3 isnow in communication with the distant attendant over line (SE39, whenlistening key N36 is operated. On being informed that a transfer toposition 2 is desired, position transfer key 138 is accordinglyoperated, closing thereby a circuit from battery, through the winding ofmarginal relay 1 it, over conductor l26,through serially connectedwindings of relay M5, to ground through the right operated contacts ofkey 138. Relay H5 now operates in this circuit, provided relay H3, H4 oranother similar relay, at some other position not shown, is notoperated. A discussion of the means whereby the control circuitfunctions so as to avoid interference, when a simultaneous attempt totransfer a call is made, is discussed hereinafter. Relay H5 with itsupper inner contacts short circuits its high resistance upper windingwhich so reduces the resistance of the circuit that marginal relay H6operates. Relay H5 continues to hold on its lower winding. Relay i itoperated; closes a circuit from ground on its left contacts overconductor 721, through upper outer operated make contacts of relay He,left operated contacts of key 138, over conductor 528, and to batterythrough winding of horizontal selecting magnet 698, which operates.Another circuit is closed from battery through the right contacts ofrelay HE, winding of relay ill to ground on the left outer breakcontacts of relay H8. Relay H'l operates relay H8 in a circuit fromground through the winding of relay H8, operated front contacts of relayl l? to battery on the operated right contacts of relay lit, to whichrelay H8 locks through its left inner cont-acts. Relay H8 in operating,opens the operating path of slow release relay 'i ii and with its rightouter contacts connects battery 729, through resistance 13% to conductor53 i, through lower outer contacts of relay H5 to conductor 333, whichis identical with conductor 333 of the cord circuit of Fig. lB. Thetracing of the circuit is now continued through lower outer contacts oflisten ing key I86 to sleeve conductor ill, thence over the sleeveconductors of plug Hi3 and jack tee, through the windings of relays 6Mand 8H? as before traced. Due to the higher voltage of battery 629,marginal relay EH5 now operates and looks from battery through its leftwinding and inner contacts to ground on the right outer operated frontcontacts of relay 6M and connects ground on its right contacts toconductor 658, thence through winding of vertical holding magnet 583,over conductor Ell to battery on the left outer back contacts of relay5M. Magnet 5&3 operates.

When relay H8 operated and slow release relay 'Hl releases, a circuit isclosed with the inner right contacts of relay 158 from battery on theright contacts of relay l l 6 through back contacts of relay 'Hl, overconductor 132 through lower 2,139,800 inserting the plug of cord circuitH2, that is,

inner contacts of relay H5, over conductor 133 to ground through releaselamp i2 I, which is lighted, indicating to the attendant that thetransferring apparatus has functioned. Key H8 is then released,releasing relays H5 and H6 and in turn magnet 6G8 and relay H8. The plugof the cord circuit is now withdrawn from jack m9, thereby opening thesleeve circuit and causing the release of relays 6M and 655. Theoriginal operating circuit of magnet 613 is opened by the removal ofground from conductor 6H5 but magnet 6 l3 remains energized from groundon conductor sit through its left contacts and winding to battery overconductor 5. By reason of the continuity contacts of relay 6 i i groundis connected to conductor 8 i8 before ground is removed from conductor656 by the release of relay M5, thereby assuring the holding of magnetEH3. A circuit is now closed for lighting lamp H32 at position 2, whichis traceable from battery on the left back contacts of relay 6 i 5, overconductor Hi9, through operated switch contacts 629, over conductors 62!and 13 through lamp 502 to ground.

If the attendant at position 2 should delay in answering, the attendantat position 3 may be recalled, relays 603 and 6M functioning as beforedescribed to light lamp W3. In this case relay EM is adjusted so thatbattery is connected to conductor H36, by its right outer contactsbefore battery is removed from conductor fill by its left outer backcontacts, magnet 5H3 remaining operated thus maintaining lamp 162lighted. When either attendant at position 2 or 3 answers by plugginginto jack m8 with the plug of the cord circuit H l, relay GM is operatedreleasing relay 6E4 thereby extinguishing lamp E03, removing ground fromconductor M8 releasing magnet M3, opening contacts 529 and therebyextinguishing lamp N32.

The means whereby interference is avoided if attendants at differentpositions attempt to transfer calls simultaneously will now bediscussed. When key !38 was operated as before described it was assumedthat the common control circuit was not then in use. Suppose, however,that the circuit is being used at positionZ, that the associated relaylid is operated and the upper high resistance winding of relay 7 I4 isshort-circuited and connected to ground through the operated rightcontacts of key 535. Under this condition the two serially connectedwindings of relay 1 l5 are accordingly shunted by the low resistancelower winding of relay H4. Relay 7 i 5 is marginal under this conditionand does not operate. Consequently position 2 encounters no interferencefrom position 3. If key should be operated simultaneously with key E38,relays I Hi and H5 would then operate together. If each relay shouldclose its upper inner front contacts simultaneously and short circuitits upper winding then the individual current flow through therespective lower windings of relays lid and H5 would be so small thatthese relays would immediately release. If now one of the relays, sayrelay :7 it should release before relay 1 i 5, then the low resistanceshunt on the lower winding of relay H5 is removed and relay H5 holds,and at the same time shunts effectively the two serially connectedwindings of relay 1 Hi, which continues in the released condition.

Referring now to the alternative arrangement in which Fig. 6 cooperateswith Fig. 8, trunks 66E, 5M and fitZ are associated with jack and lampequipment in Fig. 8, identical with that of Fig. 7. Also, the cordcircuits BH, M8 and M9, are the 'contacts to battery on conductor 821.

same as in Fig. 7. However, in Fig. 8, instead of a relay type ofcontrol circuit, a control circuit of the stepping switch type is used,which consists of a stepping magnet 88B and associated contact banks352, 883 and 886. In cooperation with the stepping switch are fourrelays 805, 886, 887 and 888. When one of the positional transfer keysas 889, 850, 8! I, 8l2 is operated, start relay 885 is operated whichcauses the control circuit to operate and associate itself with theposition from which the desired transfer is to be made. The transferringapparatus of Fig. 6 is then caused to function in the same manner as itdid in cooperation with Fig. 7. A more complete understanding of thisarrangement of the invention may be obtained from the following detaileddescription.

Let it be assumed that a call over line 608 causes the apparatus of Fig.6 to function as hereinbefore described, connecting battery toconductors 188 and 185, lighting thereby busy lamps 8M, 8I5, 8H3 andbusy lamps at positions not shown, and answering lamp M3 at position 3.The attendant at position 3 responds by inserting the plug of cordcircuit 899 into jack 828. Relay 6M operates, but relay 6E5 does notoperate. Lamp tit is extinguished and the busy lamps remain lighted asbefore described. When the listening key 16 of the cord circuit of Fig.1B, which shows cord circuit M9 in' detail, is operated communicationover line 680 is established. Assuming now that the attendant atposition 3 is requested to transfer the call, as in the case of thearrangement of Figs. 6 and 7 to position 2, position transfer key SM isaccordingly operated, thereby closing a circuit from battery through thewinding of relay 885, over conductor 82 I, through right inner contactsof key 8| l to ground. Relay 885 operates and closes a circuit fromground on its contacts, through left outer contacts of relay 896 tobattery through the interrupting contacts and winding of magnet 888.Magnet 800 now causes brush arms 822, 823, 824, 825 to rotate in thedirection indicated, beginning the rotation from any terminal on whichby chance they may rest as a result of a previous operation. When brusharm 824 makes contact with terminal 3 of bank 883, corresponding toposition 3, ground is connected through the right contacts of key 8Hover conductor 826, through said terminal 3, over brush 825 to batterythrough winding of relay 806, which operates and opens the circuitthrough the winding of stepping magnet 800, thereby stopping the switchwith all brush arms resting on the third terminals. If brush arm 824should happen to rest on the third terminal as a result of a previousoperation then relay 806 would operate immediately preventing anymovement of the switch. Relay 886 in operating also connects ground withits left inner contacts to brush arm 823, also resting on terminal 3 ofits associated bank 882. The circuit is continued over conductor 83!,through left contacts of key Bl I, over conductor E28, and thencethrough the circuit before traced in connection with the description ofthe operation of Figs. 6 and 7. Relay 806 also closes a circuit with itsright contacts from battery over conductor 82! through the winding ofrelay 8M to ground on the left outer contacts of slow operating relay808. Relay 88! operates and closes a circuit from battery on conductor82'! through the front contacts of relay 801 and winding of relay 888 toground. Relay 808 operates, releases relay 801, and locks with its leftinner Relay 888 in operating also connects battery 828 throughresistance 829 and its right outer contacts to brush arm 825, which isresting on terminal 3 of bank 868, which terminal is connected withconductor 333 which corresponds to conductor 333 of the cord circuit Cof Fig. 1B. Marginal relay M5 operates over the sleeve circuit,including sleeve conductor 125, as before described in connection withFig. '7. This is because battery 8'28 has a voltage higher than that ofthe regular sleeve battery liB'of cord circuit C of Fig. l-B. Allapparatus of Fig. 6 now functions as before described, and contacts 629of switch CB are closed. A circuit is also closed from battery onconductor 82?! through back contacts of relay 881, right inner contactsof relay 888, over conductor 83 and brush arm 822 through terminal 3 ofbank 88! and over conductor 835 to ground through position release lamp832, which lights. The attendant at position 3 is accordingly informedthat the transfer has been completed and on removing the plug of thecord circuit from jack 820, the circuit is completed through lamp 833 atposition 2, and the invention now functions as before described. Whenthe key 8!! is released, relays 885, 888 and 8118 release, and lamp 832is extinguished. If the attendant at position 2 should find it necessaryto transfer the call to still another position this can be done byoperating the proper position transfer key at position 2, the inventionthen functioning as in the case of an original call.

Position 1 of Fig. 8 is, like position 1 of Fig. 7,

arranged as a night position, so that, when night key 836 is operated,all calls incoming over line 688 cause the lamp 887 to light. Otherlines may be grouped with line 680 so that key 838 is eifective forthese lines also.

The operating of the arrangement of Figs. 6, 7 and 8 has been discussedon the basis of calls incoming over trunks 680, GM and 882. Thisarrangement is also equally well adapted to handle outgoing calls, whichmay be initiated as described for the arrangements of Figs. 1, 2 and 3and of Figs. 4 and 5.

In all of the above disclosures, it will be noted that after theincoming signal has been transferred, the attendant at the distant endcan, by

' is to be considered as being applicable to lines I00, 408 or 680.

What is claimed is:

1. In a manually operated telephone switching system arranged forproviding different kinds of service, a telephone switchboard dividedinto a plurality of sections, a plurality of two-way circuits forincoming and outgoing messages terminating at said switchboard, aprimary signal lamp path and a plurality of secondary lamp pathsconnected to each of said circuits and respectively having appearancesat different sections, a signal lamp in each of said paths constitutingan appearance, a cord circuit at each of said sections, a telephone setconnectable to each of said cord circuits, means associated with each ofsaid transfer of an incoming call signal to a lamp in 75 any desiredsecondary lamp path, switching means associated with each of saidcircuits for automatically completing the transfer of an incoming callsignal appearing in one Section to any one of the other of saidsections.

2. In a manually operated telephone switching system, according to claim1, wherein the keyset at each of said sections and the switching meansindividual to each of said circuits comprising auxiliary circuitsarranged to transfer an incoming call signal transferred to a secondarysignal lamp to one of the other secondary signal lamps at any other ofthe other of said sections as desired.

3. In a manually operated telephone switching system, according to claim1, whereby means are provided for cross-connecting each of said circuitsso that any one of said plurality of secondary signal lamp appearancesmay function as a primary signal lamp.

4. In a manually operated telephone switching system arranged to providedifferent kinds of service, a telephone switchboard divided into aplurality of sections, a plurality of trunk circuits for incoming andoutgoing messages, terminating at said switchboard, a primary signallamp path and a plurality of secondary lamp paths connected to each ofsaid circuits and respectively having appearances at different sections,a lampin each of said paths constituting an appearance,

a cord circuit at each of said sections, a telephone set connectable toeach of said cord circuits, means associated with each of said lamps forpermitting a connection between said cord circuit and each of said trunkcircuits, a keyset at each of said sections comprising means forinitiating and completing in response to a request for a particular kindof service the transfer of incoming call signals to any desiredsecondary signal lamp, and a cross-bar switch common to each group often trunk circuits and a group of transfer trunks interconnecting saidcross-bar switch and said keysets arranged to transfer an incoming callsignal transferred to a secondary signal lamp to one of the othersecondary signal lamps at anyof the other of said sections as desired.

5. In a manually operated telephone switching system, according to claim4, wherein connections are provided between an N number of saidcross-bar switches connected together horizontally for transferring whenone of said initiating keys is operated, an incoming call signalreceived over any one of ten times N number of trunk circuits from oneof said primary signal lamp appearances respectively associated withsaid trunk circuits to any one of ten positions of said switchboard.

6. In a manually operated telephone switching system, according to claim4, wherein connections are provided between an M number of saidcross-bar switches connected together vertically for transferring whenone of said initiating keys is operated, an incoming call signalreceived over any one of ten trunk circuits from one of said primarysignal lamp appearances respectively associated with said trunk circuitsto any one of ten times M number of positions of said switchboard.

7. In a manually operated telephone switching system, according to claim4, wherein connections are provided between an N number of saidcross-bar switches connected together horizontally and an M number ofsaid cross-bar switches connected together vertically for transferringwhen one of said initiating keys is operated, an incoming call signalreceived over any one of ten times N number of trunk circuits from anyone of said primary signal lamp appearances respectively associated withsaid trunk circuits to any one of ten times M number of positions ofsaid switchboard.

8. In a manually operated telephone switching system arranged to providedifferent kinds of service, a telephone switchboard divided into aplurality of primary positions and into a plurality of secondarypositions, a plurality of two-way trunk circuits for two-way messages,each trunk circuit having an appearance in said switchboard at each ofsaid primary and each of said secondary answering positions, primarytrunk signals individual toeach of said trunk circuits appearing in eachof said primary positions, secondary trunk signals individual to each ofsaid trunk circuits appearing in each of said secondary positions, acord circuit at each of said sections, a telephone set connectable toeach of said cord circuits, means associated with each of said lamps forpermitting a connection between said cord circuit and each of said trunkcircuits, a keyset at each of said positions for transferring inresponse to a request for a particular kind of service any signal,primary or secondary, to another of said positions, primary orsecondary.

9. In a manually operated telephone switching system, a telephoneswitchboard divided into a plurality of primary positions and into aplurality of secondary positions, a plurality of trunk ircuits for twoway messages, each trunk circuit having an appearance at each of saidprimary and each of said secondary positions of said switchboard,primary trunk signals individual to each of said trunk circuits,appearing at each of said primary positions, secondary trunk signalsindividual to each of said trunk circuits appearing at each of saidsecondary positions, means associated with each of said trunk circuitsfor selectively actuating the associated trunk signal at any one of saidprimary or secondary positions, transferring means associated with eachof said positions for initiating the transfer of a secondary or primarysignal to any selected position, and for initiating the transfer of asecondary or primary trunk signal to any selected position and forcausing the functioning of the selecting means aforesaid, a transfertrunk circuit common to all trunk circuits and to all switchboardpositions interconnecting said selecting means and said transferringmeans, and means whereby said transfer trunk circuit is effected for thetransfer of only one signal at a time thereby avoiding interferencebetween trunk circuits.

ALLEN RUDOLF BONORDEN.

